Influence of silicon impurity on the structure and physical properties of Sn-Si-O films

Abstract

Silicon-doped tin dioxide (Sn-Si-O) films were prepared by HF reactive ion-beam sputtering of a composite tin metal target in a controlled atmosphere of Ar and O 2. The use of a tin metal target with nonuniformly distributed quartz inserts made it possible to prepare a set of samples with a silicon impurity content of 0.5 to 4 at.% in one sputtering process. The elemental composition of the samples was determined, phase analysis was performed, and the dependence of the surface morphology of SnO 2 on the content of silicon impurities was established. It has been shown that an increase in the Si concentration in the Sn-Si-O samples leads to a decrease in the grain size of polycrystals down to a value of about 5 nm, which is confirmed by the data of XRD and high-resolution transmission electron microscopy (HRTEM). The effect of a silicon impurity in SnO 2 films on the optical properties of the films and the band gap, as well as on the concentration and mobility of charge carriers, has been studied. The films have a high transparency coefficient (over 70 %) in the visible region of the spectrum. The light transmission threshold lies in the region of 300-400 nm. When measuring the gas sensitivity of doped SnO 2 films, the influence of the grain size on the gas sensor properties of the films was established and a size effect was found, which consists in a decrease in the temperature of the maximum gas sensitivity of the films with a decrease in the grain size and with an increase in the ratio of the number of atoms on the grain surface to their number in the bulk. Silicon doping of SnO 2 films allows one to control the grain size of polycrystals and improve the metrological parameters of gas sensor elements based on SnO 2 .

Synthesis of thin-film layers of electrochromic panels based on SnO2 and WO3 by aerosol pyrolysis

“…The influence of the impurity concentration is explained as follows: antimony atoms, being donors, replace tin atoms, which leads to the appearance of excess free electrons. A slight increase in the surface resistance Rs (when a certain doping concentration is reached) is due to the fact that excess antimony atoms do not take the correct positions in the lattice [12].…”